Proteases, Protease-Derived Peptides and Protease Inhibitors Many physiological as weil as pathophysiological processes are mediated by proteases and the products of their actions, protease-derived peptides. However, the uncontrolled activity of proteases can be extraordinarily destructive and dangerous to rmal biologie systems. As a result, biology has gone to great lengths to control the activities of the proteases involved in these systems by developing aseries of both highly specific (regulatory) and n-specific (protective) anti-proteases. The protease/anti-protease balancing activities include the rmal homeostatic processes of clotting and clot lysis, hormonal regulation of blood pressure and the control of the inflammatory response represented by both the humoral (the kallikrein-kinin and complement systems) and cellular (neutrophil and macrophage derived proteases) components of the inflammation. Examples of successful therapies directed at these protease dependent systems include the use of warfarin and heparin to control thrombosis and streptokinase or tissue plasmigen activator (tPA) for the acceleration of clot dissolution. Similarly, the use of angiotensin converting enzyme (ACE, a type of limited activity protease or peptidase) inhibitors has made a significant impact on the treatment of hypertension. Lastly, the restitution of rmal antiprotease levels by the infusion of the purified protein in patients with genetic alpha-1-antiprotease deficiency is regularly being used to reduce the rate of lung function 1055 caused by the upposed activity of human neutrophil elastase in these individuals.